[REG 5.11.2->5.12.0] QJSEngine: implicit creation of a variable with the name of the key in a function of an object

QJSEngine e;

e.evaluate("\
o= {\
  a:() => { const a = 42; return a; }\
}").toString()
// "SyntaxError: Identifier a has already been declared" rather than "42"

e.evaluate("\
const a = 42; \
const o = {\
  a: () => { return a; } \
}; \
o.a()").toString()
// "function a() { [native code] }" rather than "42"

e.evaluate("\
const a = 42; \
const f = () => { return a; }; \
o = {a:f}; \
o.a()").toString()
// "42"